Fire extinguisher



y 1950 H. w. DOUGHTY 2,505,827

FIRE EXTINGUISHER I Filed Sept. 16, 1947 I FIG. 2

fi-I- a INVENTOR HOWARD WATERS DOUGHTY Patented May 2, 1950 sight)! .to .Fir x C llicl bjka {Masses corporationct Rhode Island Application-"September 16, 19. 47, serial Nc. 511433153 LASH- .6)

3 Cla -DS- This invention relates :to fire extinguishers and particularly to improvements in extinguishers which are adapted torelease a fire extinguishing agentautomatically when the=temperature in .the vicinity of the apparatus rises ;to a p ffidetermined point.

In apparatus of this type, a receptacleis provided for a fire extinguishing liquid. usually. .a chlorinated hydrocarbon such ascarbon tetrachloride and a gas generating'agent such as an aqueous solution ofammonia. The apparatus is provided with a sprinkler head or similar distributor and an outlet leading thereto which is normally sealed and adapted to bereleased when a fire occurs. generating agent when the temperature rises, and the fire extinguishing agent-is forced through the outlet when the latter is released. The fire. extinguishing agent is distributed over the surrounding area.

;The receptacle insuch extinguishers is custom= arily made of aluminum to QJVOldJOOIlOSiOIlubY the liquid contents as described-'inPatent-No. 1,698,840. Usually such extinguishersrareprovided withthe .dual control features .oiPatent No. 1,736,255. In recent forms ot-such-extinguishers, parts of the releaseimechanism"have been constructedof. stainless steel, as showntfor example in Patent No. 2,020,427. Theaextinguishers may be constructed sothat the fire extinguishing liquid is delivered upwardly through an outlet tube as shown, for example, in the last mentioned patent.

The frangible diaphragm which-is-characteristic of the dual control feature of Patent No. or

1,736,255 may be made of any suitable metallic foil of requisite strength, but usually gold foil is employed. The diaphragm-is secured between two washers of suitable material, stainless steel being commonly used. Thediaphragmmrevents the escape of any liquid from-the extinguisher until the pressure therein has risen to a point sufficientto rupture thediaphragm. The latter is ordinarily protected by means which prevents rupture until a link or cap has likewise been released by an increase of temperature suflicient to melt a low melting point alloy whereby the link or cap is held in place. Consequently the liquid is not released until the temperature is sufiiciently high to melt the alloy and also to generate gaseous pressure within the container.

In extinguishers such as I have described, the aluminum comprising the receptacle is relatively high in the electropotential series, whereas both Pressure is developedbvthegas i 13%, nickel 8% orsimilar composition) are relatively low in the same series. Theliquid contentsof the extinguisher afford anexcellent electrolyte and consequently over a period ofyears electrolytic corrosion may occur and eventually will cause failure ofthe device if a closed circuit .is maintained, permitting the flow of current between the gold. stainless steel or other similar metal-and-thegaluminum.

It is the object of the present invention to avoid, in fire extinguishers of the type described, the effects of electrolytic corrosion and conse- ,quent; failure of the apparatus.

.Other objectsand advantages of the invention will be apparent as it is better understood by reference to the following specification and the accompanying drawings, in which Fig. .,1 .is -a sectional view through an extinguisher embodying the, invention; and

Fig. 2 is an enlarged sectional view of the sprinkler ,head in such an extinguisher. Asian, exampleof the invention, and referring to the drawing'. a, receptacle 5 is made .of aluminum to avoid the chemical corrosive effect oflthe mixture of carbontetrachloride and aqueous ammoniawhichj isjstpred' in the receptacle. Infthe formgof the invention illustrated, the liquid is discharged upwardly through a tube .1. The tube 1 is connected to a plug 8 threadedly secured. in a head 9 havinga yolge l0 and a distributor ll mounted thereon. Thetube l, the plug 8 and the head 9 may be made of aluminum and are secured in an opening in the casing .5 by a collar l lalso of aluminum.

fiupportedjin the head 9 isa thimble l3 which inthe present form ofj'the, invention is also made of alumiriumand is adapted to receivea cap 14, preferably of stainless. steel covering an outlet l5'and held in; place by a low melting point solqler lfiiaroundthe-edgesof the cap. The thimble l3is lfilled preferably withva :material it which is a liquid or semi liquid r at; the. temperature at whichthejj apparatusis desig ed to operate. jVasea line and glycerine are suitable materials. Low melting point waxes and like materials can be used. The material H is designed to be ejected when the diaphragm is released to permit the expulsion of the liquid contents of the receptacle. It serves meanwhile to protect the diaphragm hereinafter described and to prevent rupture thereof until the cap it is released by the melting of the solder.

Between the flange at the lower end of the thimble l 3 and the shoulder formed by the inner gold and stainless steel (iron 74%, chromium 65 end of the plug 8, the diaphragm assembly is 3 mounted. It consists of a diaphragm l8 of aluminum foil. It is mounted between washers l9 and 20 also of aluminum, which hold the diaphragm firmly and prevent leakage of liquid around it so that no liquid can escape until the diaphragm is ruptured.

As will be seen from the foregoing, all of the parts of the extinguisher, except the cap M, which are exposed to liquids or vapors of ammonia and carbon tetrachloride, are made of aluminum, and hence there is no difference of potential between the parts and no electric current can flow between them in the presence of the electrolyte. Therefore, no electrolytic corrosion is possible, and extended life of the apparatus is assured.

In order to hold the cap i l in place so that it will be released only at a suitable temperature, low melting point solders such as Woods metal, Rose metal, Lipowitz metal, etc. are used. Ihese solders do not adhere readily to aluminum. To avoid this difficulty, I plate the end of the thimble IS with a suitable metal such as copper, brass, nickel or silver. Any of these metals can be deposited on the surface of the aluminum by ordinary electroplating, or otherwise, and the coating alfords a satisfactory base to which the low melting solder will readily adhere. I prefer to plate the end of the thimble It with silver, since this metal is not affected by the mixture of liquids such as carbon tetrachloride and aqueous ammonia or by their vapors, whereas nickel is very slightly and slowly affected and copper and its alloys may be dissolved in time by contact with such liquids and vapors. Nevertheless copper, brass and nickel will serve the purpose of affording a satisfactory base for the application of low melting point solder, since the cap is not normally in contact with the contents of the extinguisher.

The improved extinguisher as described is relatively inexpensive as compared with forms of such devices heretofore in use, and since there is no possibility of electrolytic corrosion, the apparatus can be maintained in use for many years without possibility of failure.

Various changes may be made in the structure and arrangement as described without departing from the invention or sacrificing the advantages thereof.

I claim:

1. In an automatic fire extinguisher adapted to release a fire-extinguishing liquid under pressure generated by increase in temperature in the Vicinity of the extinguisher to a predetermined point and comprising a receptacle for the fire extinguishing agent and pressure generating agent, an outlet assembly connected to the receptacle and having a discharge passage therethrough and including an outlet thimble and means normally sealing the discharge passage but adapted to burst when the pressure within the container reaches a predetermined point, the improvement in which the outlet thimble and the other parts of the outlet assembly are of aluminum so that there is no difference of potential between the parts thereof, the outlet thimble has its exposed end coated with a metal of the class consisting of copper, brass, nickel and silver, and a cap is secured to the coating by a low melting point solder.

2. In an automatic fire extinguisher adapted to release a fire-extinguishing liquid under pressure generated by increase in temperature in the vicinity of the extinguisher to a predetermined point and comprising a receptacle for the fire extinguishing agent and pressure generating agent, an outlet assembly connected to the receptacle and having a discharge passage therethrough and including an outlet thimble and a diaphragm of aluminum foil normally sealing the discharge passage but-adapted to burst when the pressure Within the container reaches a predetermined point, the improvement in which the outlet thimble and the other parts of the outlet assembly are of aluminum so that there is no difference of potential between the parts thereof, the outlet thimble has its exposed end coated with a metal of the class consisting of copper, brass, nickel and silver and a stainless steel cap is secured to the coating by a low melting point sold-er.

3. In an automatic fire extinguisher adapted to release a fire-extinguishing liouid underpressure generated by increase in temperature in the vicinity of the extinguisher to a predetermined point and comprising a receptacle for the fireextinguishing agent and pressure-generating agent, an outlet assembly connected to the top of the receptable and having a discharge passage therethrough and including an outlet thimble, means normally sealing the discharge passage but adapted to burst when the pressure within the container reaches a predetermined point and a discharge tube extending from the outlet assembly to adjacent the bottom of the receptacle, the improvement in which the receptaole, the discharge tube and the outlet thimble and the other parts of the outlet assembly are of aluminum so that there is no difference of potential between said parts, the outlet thimble has a coating at its exposed end of a metal of the class consisting of a copper, brass, nickel and silver and a cap is secured to the coating by a low melt ing point solder.

HOWARD WATERS DOUGHTY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 440,952 Land Nov. 18, 1890 2,020,427 Mossberg Nov. 12, 1935 2,081,325 Doughty May 25, 1937 FOREIGN PATENTS Number Country 7 Date 315,178 Great Britain July 11, 1929 

